Comparing Pascal, C, C++ and Java thru Code.

Hello all, I'm just beginning with programming. Started with a bit of PASCAL and now just browsing thru C,C++ and Java. Basically, I'm comparing them through code. I have this piece of code in PASCAL:
-------------------------------------------

Code:

Program A;
var
sum,x,i:integer;

Procedure AddX(x:integer);
begin
   sum:=sum+x;
end;

Begin
   i:=0;
   repeat
     read(x);
     AddX(x);
     i:=i+1;
   until i=10;
write(x);
write(sum);
End.

-----------------------------------
I'm converting them to C, C++ and Java.. to understand the differences. Here are my C and C++ samples:
-----------------------------------

Code:

#include <stdio.h>

int main()
{
   int i,x,sum;
   i=0;
   sum=0;
      do
         {
         scanf("%d", &x); 
         sum=sum+x;
         i=i+1;
         }
      while (i!=10);
   printf("%d\n", x);
   printf("%d\n", sum);

system("PAUSE");
return 0;
}

-----------------------------------------
In C++:

Code:

#include <iostream>
#include <stdlib.h>

using namespace std;

int main()
{
   int i,x,sum;
   i=0;
   sum=0;
      do
      {
         cin >> x;
         sum=sum+x;
         i++;
       }
       while (i!=10);
cout << x;
cout << sum;

system("PAUSE");
return 0;
}

---------------------------------------------------
I'd like to find out, from the experts out there, are my codes correct? Console would return the last value input and the sum. However, I'm figuring out, do I need to make a function for AddX?

I haven't started with the Java code yet. (Because I'm just browsing through Java now) But if you guys have an idea how I can do this, I'd appreciat e it very much.

After a quick read-through, the only thing I can see is that your call to pause the system at the end, should have a capital S. It's a minor thing but on most compilers I don't believe it'll work.

A few pointers, however:

System("PAUSE"); is a bad idea. You can accomplish the same thing using the getch(); function in conio.h. On the outside, it has the same characteristics and behavior, but it doesn't depend on outside programs. System("PAUSE") tells the OS to run a program called Pause.exe - and a lot of systems won't accept this. I think only Win9x and DOS.

sum=sum+x can be replaced with sum+=x. The same contraction can be used for subtraction, multiplication, and also division.

I don't think it would be fair to compare that way, only because in your pascal version you set up a procedure, which is like setting up a function. So in the others, a function should be made for that operation. It's a very small tidbit, but if you're comparing syntax and such, everything should be on the same level.

Many thanks to your comments. Here is my revised C/C++ code for the pascal sample. In your opinion, was I able to tranlate the code properly?

Code:

#include <iostream>
#include <stdlib.h>

int i,x,sum;

using namespace std;

int AddX(int x)
    {
    sum+=x;
    return sum;
    }

int main()
{   
    i=0;
    sum=0;
    do
        {
            cin >> x;
            AddX(x);
            i++; 
        }
    while (i!=10);
    cout << x << '\n';
    cout << sum;

return 0;
}

Code:

#include <stdio.h>
int i,x,sum;

int AddX(int x)
    {
    sum=sum+x;
    return sum;
    }


int main()
{
    i=0;
    sum=0;
     do
        {
            scanf("%d", &x);
            AddX(x);
            i=i+1;
        }
     while (i!=10);
        printf("%d\n", x);
        printf("%d\n", sum);

    return 0;
}

yes I do.

Originally Posted by sean_mackrory

After a quick read-through, the only thing I can see is that your call to pause the system at the end, should have a capital S.

the lower-case 's' is correct for a system call. I think in win32 you can use capital 'S'. Agreed that it shouldent be used in this situation though

>>int AddX(int x)
I believe this should be declared as void, if you want it to be exactly like the Pascal version; and if you do that, then the return statement at the end of the function shouldn't be there.

Originally Posted by Hunter2

>>int AddX(int x)
I believe this should be declared as void, if you want it to be exactly like the Pascal version; and if you do that, then the return statement at the end of the function shouldn't be there.

Good catch. Proceedures return nothing in Pascal.

Quzah.

Originally Posted by sean_mackrory

System("PAUSE"); is a bad idea. You can accomplish the same thing using the getch(); function in conio.h. On the outside, it has the same characteristics and behavior, but it doesn't depend on outside programs. System("PAUSE") tells the OS to run a program called Pause.exe - and a lot of systems won't accept this. I think only Win9x and DOS.

For a more compliant approach, however, one could put

Code:

if(cin.get()) return 0;

at the end of your document, it does the same thing as getch();, and it not borland, it's ANSI.

>>if(cin.get()) return 0;
You wouldn't need the if. Actually, the if is probably a bad thing, because if cin.get() returns false, then main() won't return a value.

1. Yes, the pascal procedure comment was correct:

procedures in pascal are basically equivalent to void functions in C/C++

Your pascal procedure should also send back the value of sum variable instead of value parameter x right? Since you are using a procedure

value = in
variable/reference= in/out, out

Because you want to send the value back to main through the parameter.

So pascal
(Try to remember..long ago..)

Code:

Procedure AddX( x:integer; var sum :integer)

begin
  
   sum:=sum+x;
end;

I also think it is bad style to just hava read statement. I would suggest having prompt with it like

Enter a value sum
read x

You get the idea..


2. Modify the pascal procedure to C/C++

3. Then try it in C#as well as Java

Overall good try

(*snip!*)

**EDIT**
Ooops, you edited There goes a lot of typing for nothing... But anyway, if you do that then the procedure call would need to be changed too, and the C/C++ samples need to be updated too. But truthfully, I don't see anything wrong with the original code; it was just used to illustrate his meaning.

Hunter

The := in the C/C++ was a typo.

Could not remember the scope rules for pascal.

Just curious if he actually did run and compile that pascal program.

Originally Posted by Hunter2

>>if(cin.get()) return 0;
You wouldn't need the if. Actually, the if is probably a bad thing, because if cin.get() returns false, then main() won't return a value.

Very good point. One must make up for that then, I suppose.

Originally Posted by Hunter2

>>int AddX(int x)
I believe this should be declared as void, if you want it to be exactly like the Pascal version; and if you do that, then the return statement at the end of the function shouldn't be there.

Wow. Thanks for the info. Let me redo the code again...